Renewable electric fuse



Aug. 26 1924. 1,506,049

s. B. coNDlT, JR

RENEWABLE ELECTRIC FUSE Filed June '7, 1919 Patented ug. 26, 1924.

UNITED STATES PATENT OFFICE.

SEARS IB. CONDIT, JR., OF BROOKLINE, MASSACHUSETTS, ASSIGNOR TO CONDIT ELEC- TRICAL MANUFACTURING COMFANY,

CORPORATION OF IVIASSACHUSETTS.

OF SOUTH BOSTON, MASSACHUSETTS, A

RENEWABLE ELECTRIC FUSE.

Application ile. June Y,

To ML whom t may conce/Mt.'

Be it known that I, SEARS B. OoNDrr, Jr., a citizen of the United States, and resident of Brookline, in the county of Norfolk and State o Massachusetts, have invented an Improvement. in Renewable Electric Fuses, of which the following is a specification.

This invention relates to a renewable electric fuse of the cartridge type.

The object of my invention is the provision of a fuse of the type above set forth having a tortuous gas vent through which the heated gas formed upon the blowing or the fuse is expelled, thereby to prevent the destruction o1 the insulating tubular enclosing casing, and also having means by which the heated gases are cooled previous to their discharge from the fuse thereby to prevent the expulsion of a dangerous flame.

Certain features herein shown, but not claimed, are shown and claimed in my copending application Serial No. 302,517, tiled June 7, 1919.

Fig. l is a side View partly in section, or' a renewable fuse embodying my i1 vention.

`F ig. 2 is a sectional view of an end cap along lines 2-2 or Fig. 1.

Fig. 3 is a front view of an end cap with the battle plate removed.

Fig. et is a front view of the battle plate.

Fig. 5 is a section along lines 5-5 of Fig. 4.

Fig. 6 is a front view oi an end 'lei-rule of the fuse casing.

Fig. 7 is a front view or the 'fuse clamping plate.

Fig. 8 is an enlarged sectional view oi' an end cap talren along its central axis and illustrating' more particularly the manner in which the'balile or pressure plate is forced into the end cap.

As here shown, the renewable fuse comprises the tubular casing 10 of suitable insulating material as fiber, having the exteriorly threaded end-ferrules 11 secured on the ends thereol2 by suitable means, as by pins 12. Said ferrules are :formed with end-portions 11a having arcuate fuse-receiving openings 11b herein. Said end-portions, at such openings, are formed with the straight edges 11c over which the ends of the renewable fusible element or strip 13 extended within said tubular casing are adapted to be reflexed. Fuse clamping 1919. Serial No., 302,51.

plates comprising the discs la having slight ly less diameter than the end errules are adapted to be pressed against the reliexed ends of the luse strip to force the ends against the end-portions o1 the errules whereby to secure good electrical contact between said l'use and errules. Said fuseengaging plates are lormed with raised projections 14n having the substantially straight lower edges 14E". Said projections are adapted to be received in the openings 11b of said lferrules to loch said plates against rotation when the end-caps of the inse are screwed in place.

The end-caps have the interiorly threaded tubular portions 15 adapted to be removably received upon the exteriorly-threaded end-ferrules or the fuse, and the end-walls 15a integrally formed with said tubular-portions.

Each ot' said end-walls has an axial vent i6 therein termed as by forcing a suitably shaped tool therethrough and by such operation forming the inwardly directed projection or nozzle 1T through which the vent extends. rl`he cross-section of said vent is gradually enlarged from the tip of said projection to the outer face of the end of the end-cap, as shown.

A baille-plate 19 comprising the concave or dished disc formed with the flattened central portion 19LL and the outer or peripheral portion 19b is received in the end cap at the bottom thereof and encloses a space therebetween and the end-wall of t-he end cap into which said projection 17 extends, but not to such an extent as to cont-act with said battle-plate. Said baille-plate has peripheral notches 19C through which gas is adapted to pass to be expelled through the vent 1G. Said baliCle-plate is preferably formed as a member separate from the end cap and oia diameter slightly less than the inner diameter ol` the end cap whereby it may be received therein. The edge or said bailleplate is relatively sharp, as indicated at 19d, and after the plate is in position in the end cap it is struck a blow to iinbed its edge in the junction between the tubular portion and the end-wall of the end cap whereby it will vbe retained in place. When the end cap is screwed onto the end of the fuse the flattened central portion 19a of the baille plate is adapted to en ge the fuse engaging plate 14 thereby to torce and hold it firmly against the refleXed end oit the fusible element; and it thereby serves as a pressure plate.

It will be noted that by the arrangeinf of the baiiie-plate the end cap is provid l with double end walls and, in connection with the vents, a tortuous passage provided for the expulsion of gas from the fuse, it being necessary for the gas to flow from the space between the :fuse-engaging plate 14. and the baille-plate through the peripheral passages 19C therein and then toward the axis of the fuse to he again alvtered in direction for expulsion through the vent. The fuse-clamping plate also servesI to direct the gas from the interior of the fuse casing more or less radially outward into the space between it and the bailleplate and in itself functions as a baille-plate to reduce the expulsion velocity oi? the gas. The fuse-clamping plate, baffle-plate and end cap are made, usually, of copper or copper composition and have a relatively great ability to abstract heat. The healed gas as it is expelled from the fuse is directed into contact with these relatively cold bodies and as a consequence has a considerable portion of its heat removed, so that the gas is relatively cold and thereby without flame when finally expelled from the fuse.

If desirable the space between the barileplate and the end-wall of the end cap may contain a porous body 2O as asbestos,` ste wool and the like toi additionally reduce the expulsion velocity of the gas and at the same time to cool it.

l. A renewable electric iuse of the cartridge type comprising the combination et a tubular enclosing casing, an exteriorly screw-threaded ferrule having an aperture end wall carried by the end of said casi1 and an internally screw-threaded end cap having an end wall formed with an aperture therethrough, and a dished pressure plate received in said end cap over the aperti in' said end wall and with its periphf. A, in secure frictional engagement with said end cap and having eccentrically dispo gas passages therethrough, said pressure plate arranged to press the end of a element against the end wall oi' said rule.

2. An end cap for a renewable electric fuse ol the cartridge type having an inter nally screw-threaded tubular portion, d an end wall having an inwardly dire projection formed' with a vent therein, and a dished plate having notches in its pe-v riphery and having its periphery in lirictional contact with the end cap in a projection-covering position and spaced .troni said end wall to provide a gas passage from the notches through said vent.

3. An end cap for a renewable electric fuse oit the cartridge type having an internally screw-threaded tubular portion and an end wall having an inwardly directed projection formed with a vent therein, and an apertured dished plate tixed in said tubir lar portion to enclose said projection and provide a gas passage between it and said vent.

4i. [in end cap for a renewable electric fuse of the cartridge type comprising an interiorly-threaded tubular-portion adapted te be removably received on the end ot the fuse, and an end-wall having an axial vent therein, and a bathe-plate comprising a disc arranged in said cap in front ot said vent having its peripheral portion embedded in said tubular portion and having notches providing gas passages in :its periphery.

5. An end cap lor a renewable electric fuse of the cartridge type comprising an interiorly-threaded tubular-portion adapted to be removable received on the fuse, and an end-wall having an axially arranged inwardly directed projection formed with a vent therein, and a concave disc arranged within said cap over said projection havin its peripheral portion embedded in said en cap and having peripheral gas passages therethrough.

G. An end cap for a renewable electric fuse of the cartridge type comprising an interiorly-threaded tubular-portion adapted to be removably received on the fuse, and an end-wall having an inwardly directed projection formed with a vent therein, a concave disc arranged within said cap over said projection having its peripheral portion embedded in said end cap and having peripheral notches providing` gas passages between it and the tubular portion and a porous body received in the space between said disc and the end-portion of said endcap.

7. An end cap for a renewable electric tuse of the cartridge type having an interiorlv threadid tubular portion and an end wall 'with an axially arranged, inwardly extended projection with a vent opening therein, a da concave disc fixed in said end cap over said projection with its periphery elnhedded in the junction between said tubular portion and end-wall, said disc having pe ripheral notches therein forming gas passages 'troni the fuse to the vent opening.

8. L renewable enclosed electric fuse of ine cartridge type comprising an enclosing tubular casing, exteriorly-threaded end teri'ules received thereon having fuse-supporting portions arranged over the ends of the casing with fuse-receiving openings therethrough, a fuse strip extended through said openings having its end portions reiiexed over the faces of said fuse-supporting portions, fuse clamping plates engaging vthe relexed ends of Said fuse strip, and end caps removably received on said end errnles having interiorly threaded tubular portions and end Walls formed with axially arranged inwardly directed projections having vents therein, and concave discs arranged in said end-caps having their peripheral portions embedded in the junction between the tubular portions and end Walls thereof, said discs having peripheral notches providing gas passages from the casing to the rents.

9. In a cartridge fuse an end Closure ferrule having its side Wall internally7 threaded at its attaching portion and plain in the outer portion thereof, a Washer located in said nnthreaded portion of the errule in assembled condition, and a vent opening in the outer end of the ferrulc, Said vent opening lying within the area defined by the washer.

ln testimony whereof, I have signed my name to this specification, in the presence` of two enscribing Witnesses,

B, coNniT, JR.

lllitnesses GEORGE A. BURNHAM, DANmL S. VLsoN. 

